1. Field of the Invention
The present invention relates to a magnetic tape cartridge comprising a single reel having magnetic tape wrapped therearound, rotatably housed within a cartridge case. Particularly, the present invention relates to the structure of the cartridge case.
2. Description of the Related Art
There are known magnetic tape cartridges of the type wherein a single reel having magnetic tape wrapped therearound is rotatably housed within a cartridge case, as disclosed in, for example, Japanese Unexamined Patent Publication Nos.11 (1999)-306722, 2001-148179, and 2001-266533. These magnetic tape cartridges are conventionally employed as recording media in external memory devices for computers and the like.
FIG. 10 is a perspective view that shows the entirety of a magnetic tape cartridge 1 of this type, in a state in which a slide door 11 is open. A tape extraction opening 10 is formed on a side wall of a cartridge case 4 formed by fixing an upper case 2 and a lower case 3. The tape extraction opening 10 is formed across the upper case 2 and the lower case 3, in the vicinity of a corner. The slide door 11 for opening and closing the opening 10 is slidably provided therein. A magnetic tape 6 is employed to store data for a computer or the like. A leader pin 5 for extraction of the magnetic tape 6 is fixedly attached to a distal end thereof. When the magnetic tape cartridge 1 is loaded into a recording/reproducing apparatus, a pin holding member of the recording/reproducing apparatus engages the leader pin 5, pulls the magnetic tape 6 out from the cartridge case 4, and performs loading of the magnetic tape 6 into the recording/reproducing apparatus. During an unloading operation, the magnetic tape 6 is wound onto a reel 7, and the pin holding member returns the leader pin 5 to within the cartridge case 4.
The cartridge case 4 is formed by fastening the upper case 2 and the lower case 3, formed from synthetic resin, to each other with a plurality of screws (as disclosed in Japanese Unexamined Patent Publication No. 2001-148179). Alternatively, the cartridge case 4 may be formed by integrating the upper case 2 and the lower case 3 via ultrasonic welding of abutment surfaces of each of the side walls thereof (as disclosed in Japanese Unexamined Patent Publication No. 2001-266533). The leader pin 5, with its axis being oriented vertically, is removably held in the vicinity of the tape extraction opening 10 straddling the upper case 2 and the lower case 3. The slide door 11 for opening and closing the tape extraction opening 10 is urged toward the closed position by a spring.
In the magnetic tape cartridge 1 having the construction as described above, the tape extraction opening 10 is formed in the vicinity of a corner of the cartridge case 4, which is square in shape. Space for a tape path, as well as space for a path for the pin holding member of the recording/reproducing apparatus needs to be secured in the periphery of the position within the opening 10 at which the leader pin 5 is housed. Therefore, screws for fixing the upper case 2 and the lower case 3 cannot be provided at this position, but are provided at positions remote from this area (as disclosed in Japanese Unexamined Patent Publication No. 2001-148179). There is no side wall in the cartridge case 4 where the opening 10 is provided. In addition, there is no portion in the vicinity of the tape extraction opening 10 which is fixed by screws. Further, a groove 20 for guiding the leader pin 5 is formed in the bottom surface of the lower case 3. Accordingly, the structural integrity of the cartridge case at this portion is low.
During handling of the magnetic tape cartridge 1, there is a possibility that the cartridge 1 maybe dropped on the floor. If the corner having the tape extraction opening 10, that is, the portion having the lowest strength, strikes the floor when the cartridge 1 is dropped, the probability that the cartridge case 4 will crack at that portion, thereby damaging the magnetic tape cartridge 1, is high.
In order to improve the bonding strength between the upper case and the lower case, ultrasonic welding of the upper case and the lower case has been considered (as disclosed in Japanese Unexamined Patent Publication No. 2001-266533). However, simply welding the abutment surfaces of the upper case and the lower case to each other does not yield sufficient strength. The welded abutment surfaces may act as breaking lines, causing the side walls to bend inward when the cartridge is dropped.